Silver Angel cam tool
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I too am interested in finding out anything I can on making the silver angel cam. I wasn't aware that a special tool was needed to machine this cam, but I certainly have questions about how it is made.--Brian rupnow
The cam on this engine is a circular disc running on a vertical shaft. A roller on the end of the exhaust valve rocker arm runs on this disc, to operate the exhaust valve. I can understand that the flat area on this disk matches the "0 lift" portion of a conventional cam, and that the high point on the disc matches the high spot on a conventional cam, but I'm uncertain of the ramp on both sides of that high spot. I have heard a rumour that a special tool was required to make this cam, but I can't confirm this. If anyone has experience with this engine, or any engine with this style of cam, I would love to learn a bit more about it.---Brian Rupnow
Yes, I think I have to agree with everybody.--It would be mostly a file job in the end. However, the whole thing can first be turned on a lathe, then all of the ring at the top milled away except for the cam area. The rest could be taken down with a file. These little hit and miss engines are very forgiving in regards to the profile of the cam. Something that helps immensely is that the cam follower on the end of the rocker arm is round like a bearing, so there would be no danger of it "slapping" against the side of the ramp like a tappet would. I would make this part and the cam follower out of 01 steel, then flame harden and temper it. Probably none of us would live long enough to see it wear out.----Brian
I just did a big rootle thru the internet looking at "Domestic Stovepipe" hit and miss engines. They have the same funky exhaust cam as the Silver Angel. Lots of pictures and videos, but nothing showing on the governor. There appears to be a second shaft running almost parallel to the sideshaft, which operates a bell crank to lock out the exhaust valve lifter, but nowhere did I see a picture of the actual governor. The governor appears to be hidden between the flywheel and the engine frame. Does anybody have clearer pictures of this governor area on the engine?
Brian.
Everything looks concentric in your pic. Could it be that the governor lowers the height of the cam as the bobweights move out. Thereby gradually closing the exhaust valve to control speed. It looks like the exhaust valve spring is as weak as the inlet in you pic.
Scratch that. I looked at the engine on YT and can see that the exhaust valve is held open by the secondary lever when the bobweights move out
Everything looks concentric in your pic. Could it be that the governor lowers the height of the cam as the bobweights move out. Thereby gradually closing the exhaust valve to control speed. It looks like the exhaust valve spring is as weak as the inlet in you pic.
Scratch that. I looked at the engine on YT and can see that the exhaust valve is held open by the secondary lever when the bobweights move out
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You don't need any special fixtures just a mill and rotary table after you have turned the blank then a file to knock off the external corners.
Unlike the Domestic drawings I see the Angle ones don't give the duration (length of the high bit) of the cam
so start with one that is over size and take a bit off if needed.
Unlike the Domestic drawings I see the Angle ones don't give the duration (length of the high bit) of the cam
so start with one that is over size and take a bit off if needed.
Thank you gentlemen for your help. CWelkie, that picture in the lower left hand corner of your post is exactly what I was looking for.---Brian
Harry Wessels
New Member
I have several unfinished engines (NAMES) at about 90%, have plans.
fustrated with governor
could spare gear + cam for other parts
Also looking for DIY CNC info, have Velmex UniSlide XYZ
check out www.coolmodelengines.com
Harry
